The invention relates to a method and device for increasing bone size or mass. In particular, the present invention relates to a method and apparatus for distraction osteogenesis. The present invention especially relates to increasing size of a portion of a patient""s jawbone.
In the context of certain medical and dental procedures, it may be desirable to increase the volume of bone at certain locations. The desire to increase bone volume may arise from a desire to strengthen a weak area in a bone. Another reason for increasing bone volume is to provide sufficient volume to accommodate a device implanted into the bone.
One method for increasing bone volume involves removing bone from one part of the body and transplanting to the area where it is desired to increase the bone volume. Bone implant procedures involve major surgery and disruption to the patient""s body, wherein a patient""s body is opened. Bone to be transplanted is then physically removed from a bone with saws and/or chisels, for example. One area where bone is often removed from is the ribs, another is the hip. The area that the bone is to be transplanted to is then cut open and a proper site prepared for receiving the transplanted bone. The transplanted bone is then transferred to the site. Bone transplant typically involves major surgery involving full anesthesia.
An alternative to bone implant surgery for increasing bone volume involves a process known as distraction osteogenesis. In distraction osteogenesis procedures, bone is stretched.
Typically, an incision is made between two portions of bone and the portions of bone are then slowly separated from each other. It is desired that the space created by a separation of the bone portions is then filled in by new bone.
The present invention provides a distraction osteogenesis fixture. The fixture includes a lower anchor to be anchored in a jawbone. At least a portion of the lower anchor is externally threaded. Additionally, at least a portion of the lower anchor includes an anti-rotational feature. The lower anchor also includes an internal passage. At least a portion of the internal passage is threaded. The fixture also includes a translational screw. At least a portion of the translational screw is externally threaded such that the translational screw is receivable via threaded internal passage of the lower anchor.
The fixture further includes an upper anchor having an internal passage for receiving a portion of the lower anchor and has an anti-rotational feature for engaging the anti-rotational feature of the lower anchor. The internal passage of the upper anchor includes a surface for engaging the translational screw. At least a portion of the upper anchor is externally threaded.
The present invention also provides a distraction osteogenesis method. The method includes forming a hole in a bone of a patient. The distraction osteogenesis fixture, including a lower anchor, an upper anchor, and a translational screw, is inserted into the hole. The lower anchor includes an externally threaded portion, an anti-rotational feature, and a threaded internal passage. The translational screw of the distraction osteogenesis fixture is inserted into the threaded internal passage of the lower anchor. An upper anchor of the distraction osteogenesis fixture is attached over the anti-rotational feature of the lower anchor and over the translational screw. The upper anchor includes an internal passage for receiving a portion of the lower anchor and has an anti-rotational feature for engaging the anti-rotational feature of the lower anchor. The internal passage of the upper anchor includes a surface for engaging the translational screw. At least a portion of the upper anchor is externally threaded. At least the cortical portion of the bone is cut. The translational screw is then rotated so as to cause linear translational movement of the upper anchor relative to the lower anchor, whereby the bone surrounding the upper anchor is moved away from the bone surrounding the lower anchor.
Still other objects and advantages of the present invention will become readily apparent to those skilled in the art from the following detailed description, wherein there are shown and described only the preferred embodiments of the invention, simply by way of illustration of the best mode contemplated of carrying out the invention. As will be realized, the invention is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, without departing from the invention. Accordingly, the drawings and description are to be regarded as illustrative in nature and not as restrictive.